Mindscape recently announced Web Workbench, a new extension that adds Sass, LESS, and CoffeeScript functionality to Visual Studio 2010.
Sass and LESS are meta-languages meant to simplify and improve the reusability of CSS3 by introducing nesting, variables, inheritance, mixins, and other enhancements. CoffeeScript is a language similar to Python that improves JavaScript’s readability and conciseness, works with existing libraries, and compiles directly to JavaScript. These tools have been popular in other platforms for some time, but this is their first introduction as an extension to the Visual Studio environment.
Web Workbench includes syntax highlighting and Intellisense support, and automatically generates Javascript and CSS in a web project. As Mindscape notes, it’s not necessary to use all three languages:
If you only want Coffee Script, or only wanted to use Less, then by all means just use those parts. It's all in one install but there's no reliance on each other in your applications.
Web Workbench is available for free from the Visual Studio Gallery, or can be installed via the Visual Studio Extension Manager.